WHEN IS A CENTRAL EXTRACTION SYSTEM NEEDED?
This question is often asked in counseling sessions. To clarify this, we need to take a closer look at the functions and application options of a central extraction system. To understand whether a central extraction system is the right solution, the components must be considered in detail.
FIXED INSTALLATION EXTRACTION SYSTEM COMPONENTS
The optimum selection and design of system components for the respective application and the best possible coordination of components result in a robust extraction system. In addition to special application conditions, applicable regulations and guidelines should be considered when designing the extraction system.
An extraction system normally consists of the following components:
FILTER UNIT:
The filter unit is the core of an extraction system. The better the design and function of the filter unit, the better the separation result. E.g; The purer the air after filtration, the better.
The filter unit consists of filter media or filter elements attached to the filter housing. Depending on the application, filter bags, filter cartridges or filter cassettes are used as filter elements in dry separation, and a water bath is used in wet filtration.
Filter elements in dry separation are generally cleanable. This ensures stable extraction performance and low operating costs. To guarantee effective separation, the number and design of filter elements must be suitable for the medium to be removed. To prevent the filters from clogging, the filter surface load (the ratio of the filter area to the drawn air volume per hour) must not exceed a defined limit value.
Another important factor is the ingress of dusty air into the filter housing. The air should flow as evenly as possible to the filter elements while maintaining a low upward flow rate in the filter unit. Thus, the filter elements can be cleaned effectively during the suction process.
As a general rule, the higher the quality of the filter material, the lower the flow rate and filter surface load in the filter unit, and the finer the filter cleaning, the better the filter will perform and the longer its service life. In practice this means low operating costs for the user.
VACUUM GENERATOR:
The vacuum generator of a central extraction system provides the required air volume flow. It is generally distinguished as low vacuum generators, medium vacuum generators and high vacuum generators. Medium vacuum and high vacuum generators are especially important for dust extraction systems. Medium vacuum generators are generally fans used for applications where the collection and extraction of dusty air is required. Negative pressure is about 8,000 Pa at medium to high air volumes. High vacuum generators include side channel compressors and rotary piston or screw compressors. They are used in applications where accumulated material must be "received" and transported through high resistance pipelines. The negative pressure is high (from 140 mbar) and very small volumes of air flow.
To obtain a satisfactory extraction result, it is important to select the appropriate vacuum generator and design it according to the requirements of the particular application. Important factors; For example, the number of suction points and their simultaneity, the connection diameter at the suction points, the required conveying speed of the material to be drawn and the length of the suction lines.
The vacuum generator is usually placed next to the filter unit. Due to the increasing demands for low noise emissions, vacuum generators are installed in enclosures that reduce operating noise and also act as weather protection in the outdoor environment.
DUST DISCHARGE:
The dust evacuation is located in a central evacuation system directly below the filter unit and ensures that particles separated from the air volume flow are carried through the filter unit. As standard, collection bins, drums or drawers are used, which are connected to the filter unit with a cone. It is important that the volume of the collection container is sufficient for the resulting dust. If the collection containers are too small, emptying is often neglected and the separated residues will accumulate in the filter unit, resulting in reduced performance.
For hazardous materials, low dust disposal of separated dirt is required.
For large dirt deposits, automatic draining elements such as rotary valves or drain gate valves or flaps are recommended, which continuously deliver the material through the filter unit.
CONTROL UNIT:
The control unit - often called the control cabinet - controls all important functions of the central extraction system and ensures error-free operation. Numerous sensors now allow continuous monitoring of the most important system functions and the almost fully automatic operation of the system. For example, the suction performance can be adjusted according to current requirements, according to the number of points to be drawn or also the dust load in the air stream. This ensures low operating costs thanks to low power and compressed air consumption. Pending maintenance or service work can now be determined based on performance data – no longer simply through a fixed number of operating hours as in the past.
The control unit of the extraction system, together with more powerful sensor technology and advanced software, makes it possible today (and above all in the future) to optimally adapt the system to the respective application.
OTHER COMPONENTS
More broadly, the following components also belong to a central extraction system:
Suction pipe
Pre-separator
Heat recovery
Return / exhaust duct
For a satisfactory, long-term and economical operation of an extraction system, optimum adaptation of the components to each other and to the respective application is essential.